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CW 302
B. Demoen
Marking in the presence of destructive assignment is suboptimal
Abstract
Early reset (or virtual backtracking) consists of an action performed by the collector, while normally it is performed by the mutator. Roughly speaking, the precondition for early reset is that a cell is not useful for the forward continuation. Later reference from the trail completes the picture. When the precondition for early reset does not hold because the cell is marked, and in the context of backtrackable destructive assignment by value trailing, the usual approach to early reset is safe but suboptimal. This is explained by one example. In spirit with other pathological examples that show suboptimality of supposedly well understood reachability issues, choicepoint trimming is crucial. The relation with a rejuvenating collector and an alternative implementation of backtracking destructive assignment is discussed.
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